Generally compression techniques take one of two popular approaches. The first approach is referred to as lossless compression. With lossless compression every bit in the original data file that is compressed is recovered when it is subsequently decompressed. Because every bit is recovered and restored with lossless compression, the technique does not substantially reduce the size of the original data file that is compressed. Therefore, lossless compression is a popular technique for compressing text, word processing documents, and spreadsheets where loss of any data can be catastrophic.
The second approach is referred to as lossy compression. With lossy compression a certain amount of information or bits are generally not recoverable when an original data file that is compressed is subsequently decompressed. Generally, a user may not detect the information that was lost with lossy compression because lossy compression is generally used with large data files, such as audio and video and occasional bit losses may go undetected by the user. The benefit of lossy compression is that a more substantial reduction in the size of the original data file can be achieved in the compressed version of the original data file.
However, users are becoming more discerning and are demanding better quality media data (e.g., video, image, audio, graphics, etc.). Therefore, what use to be considered acceptable data loss with lossy compression is rapidly becoming unacceptable to users with higher-speed Internet connections, higher quality processing devices having more memory, and higher quality displays.
Further, lossless compression is not an acceptable alternative for media data compression because it cannot achieve acceptable reductions in the size of media streams that were compressed with a lossless technique.
Therefore, an alternative approach, which can retain the quality that is associated with lossless compression and which can simultaneously achieve the size reduction that is associated with lossy compression, is needed.